Codes PO171, PO174

[bobbm1]

System Adaptive fuel too lean. Did a search on this and most of what I found seemed to be for the sohc. There is no difference in how it runs/idles. No big change in milage. The Downstream and bank 2 O2 sensors have been replaced but bank 1 has not. I reset the code using a scan tool (autozone) and will see if it comes back. In the mean time any ideas?


Thanks

bobbm1

 

[griggs]

My Ford OBDII Service manual has a lot to say about having both P0171 and P0174. mainly indicates PCM is at fuel richest correction it can make and mixture is still too lean. presuming your O2 sensors are working, therefore telling you the truth (another test) then you have a problem. There is BIG long list of possible causes in the manual. vacuum leaks, Restricted air inlet etc etc. Recommend you make sure the HEGOs are all working. A shop who can diagnose that by enrichening the mixture while monitoring the HEGO voltage outputs is worth their money. And, yes, my bet is that the codes will return. If you want to dig into it yourself I can email you the diagnostic section from the manual (2 pages jpeg). Good luck Gerald Riggs "griggs@centurytel.net"

 

[bobbm1]

This might be a stupid question but I know my air filter is due to be changed could that cause this error? and yes I would love to have the diagnostics from the manual.

rmaring@columbus.rr.com

 

[bobbm1]

from the diagnostics you sent me it looks like it is a pretty sensitive system. So could a dirty air filter do this?